Aznar M C, Medin J, Hemdal B, Thilander Klang A, Bøtter-Jensen L, Mattsson S
Radiation Research Department, Risoe National Laboratory, DK-4000 Roskilde, Denmark.
Radiat Prot Dosimetry. 2005;114(1-3):444-9. doi: 10.1093/rpd/nch560.
In a previous experimental study, a novel method for in vivo dosimetry has been investigated, based on radioluminescence (RL) and optically stimulated luminescence (OSL). However, because of the large difference in atomic composition between the detector material and the breast tissue, relatively large energy dependence in low-energy X-ray beams can be expected. In the present work, the energy dependence of Al2O3:C crystals was modelled with the Monte Carlo code EGSnrc using three types of X-ray spectra. The results obtained (5.6-7.3%) agree with a previously determined experimental result (9%) within the combined standard uncertainty of the two methods. The influence of the size of the crystal on the energy dependence was investigated together with the effect of varying the thickness of the surrounding light-protective material. The results obtained indicate a minor effect owing to the thickness of the light-protective material, and a somewhat larger effect from reducing the diameter of the crystal. The outcome of this study can be used to improve the future design of the RL/OSL dosimetry system for use in mammography.
在之前的一项实验研究中，基于辐射发光（RL）和光激励发光（OSL），对一种用于体内剂量测定的新方法进行了研究。然而，由于探测器材料与乳腺组织之间原子组成存在较大差异，预计在低能X射线束中会有相对较大的能量依赖性。在本工作中，使用蒙特卡罗代码EGSnrc，利用三种类型的X射线光谱对Al2O3:C晶体的能量依赖性进行了建模。所得结果（5.6 - 7.3%）与先前确定的实验结果（9%）在两种方法的合成标准不确定度范围内相符。研究了晶体尺寸对能量依赖性的影响以及改变周围光防护材料厚度的影响。所得结果表明，光防护材料厚度的影响较小，而减小晶体直径的影响稍大一些。本研究结果可用于改进未来用于乳腺摄影的RL/OSL剂量测定系统的设计。
